Browsing by Subject "Biomechanical phenomena"

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    Fatigue-driven compliance increase and collagen unravelling in mechanically tested anterior cruciate ligament
    (Springer Nature, 2023-05-26) Putera, Kevin H.; Kim, Jinhee; Baek, So Young; Schlecht, Stephen H.; Beaulieu, Mélanie L.; Haritos, Victoria; Arruda, Ellen M.; Ashton-Miller, James A.; Wojtys, Edward M.; Banaszak Holl, Mark M.; Orthopaedic Surgery, School of Medicine
    Approximately 300,000 anterior cruciate ligament (ACL) tears occur annually in the United States, half of which lead to the onset of knee osteoarthritis within 10 years of injury. Repetitive loading is known to result in fatigue damage of both ligament and tendon in the form of collagen unravelling, which can lead to structural failure. However, the relationship between tissue's structural, compositional, and mechanical changes are poorly understood. Herein we show that repetitive submaximal loading of cadaver knees causes an increase in co-localised induction of collagen unravelling and tissue compliance, especially in regions of greater mineralisation at the ACL femoral enthesis. Upon 100 cycles of 4× bodyweight knee loading, the ACL exhibited greater unravelled collagen in highly mineralized regions across varying levels of stiffness domains as compared to unloaded controls. A decrease in the total area of the most rigid domain, and an increase in the total area of the most compliant domain was also found. The results highlight fatigue-driven changes in both protein structure and mechanics in the more mineralized regions of the ACL enthesis, a known site of clinical ACL failure. The results provide a starting point for designing studies to limit ligament overuse injury.
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    Python tooth-inspired fixation device for enhanced rotator cuff repair
    (American Association for the Advancement of Science, 2024) Kurtaliaj, Iden; Hoppe, Ethan D.; Huang, Yuxuan; Ju, David; Sandler, Jacob A.; Yoon, Donghwan; Smith, Lester J.; Betancur, Silvio Torres; Effiong, Linda; Gardner, Thomas; Tedesco, Liana; Desai, Sohil; Birman, Victor; Levine, William N.; Genin, Guy M.; Thomopoulos, Stavros; Radiology and Imaging Sciences, School of Medicine
    Rotator cuff repair surgeries fail frequently, with 20 to 94% of the 600,000 repairs performed annually in the United States resulting in retearing of the rotator cuff. The most common cause of failure is sutures tearing through tendons at grasping points. To address this issue, we drew inspiration from the specialized teeth of snakes of the Pythonoidea superfamily, which grasp soft tissues without tearing. To apply this nondamaging gripping approach to the surgical repair of tendon, we developed and optimized a python tooth-inspired device as an adjunct to current rotator cuff suture repair and found that it nearly doubled repair strength. Integrated simulations, 3D printing, and ex vivo experiments revealed a relationship between tooth shape and grasping mechanics, enabling optimization of the clinically relevant device that substantially enhances rotator cuff repair by distributing stresses over the attachment footprint. This approach suggests an alternative to traditional suturing paradigms and may reduce the risk of tendon retearing after rotator cuff repair.